The Hole Story

49, J. Gough, "High Speed Machining for Toolmaking Applications," Precision Toolmaker, 8(3), pp. 154, 157. (Apr. 1990). High speed machining concepts learned for aerospace components have been successfully applied to tool and mold making materials (e.g. A5056, A5083 A1, Cu). The use of the Matsuura FX-5 high speed machining center is discussed in light of its ability to overcome corner drop and the ability to withstand inertial loads. It is capable of roughing at 8000 mm/min and finishing at 30004000 mm/min. Contouring 3-D parts is accelerated by a high speed converter that takes the computer data and converts to 8 ms binary code. This combination of properties gives the FX-5 the ability to operate at high feed rates without loss of position or contour accuracy and can follow small axis moves without loosing position. 50, W. Bruckner, "High Velocity Lathe Milling--an Alternative or the Solution to a Problem?," VDI Z., 132(4), pp. 67, 70-72. (Apr. 1990). Details are presented on the Heynumat 5 lathe milling machine. This machine has four axes, a bed length of 850 mm, a support span of 450 mm and can operate by CNC, at cutting rates up to 4500 m/min. Particular advantages of the machine are the generation of small chips, low roughness on cut surfaces, close dimensional accuracy, high machining rates, capability to cut materials difficult to machine. Materials mentioned include AICuMgPbF38, TiAI6V4, gray iron. 2 ref. (German) 51, G. P. Kokoulin, V. D. Vodyanik, S. F. Popova, Y. S. Fedotov, "High-speed Grinding of Bearing Races," Soviet Engineering Research, 9(5), pp. 120-121. (1989). One of the main ways in which productivity and job quality in grinding operations can be improved is by increasing the wheel speed to 80 m/sec or even more. High-speed grinding of bearing races imposes extra demands on the machining system, which require the solution of a number of problems. As a result of tests at the Kursk GPZ-20 Bearing Works (in which type 6-209 bearing races were ground) it was found that in high-speed grinding the main factors determining machining accuracy are delay in passing a command to stop the machining process and allowance removal rate in the last revolution of the work before withdrawal of the workhead. 2 Refs. 52, R. Goodwin, "The Hole Story," A Cutting Edge for the 1990s, 1989. The Institute of Metals. 1 Carlton House Terrace, London SW1Y 5DB, UK. The twist drill is gaining in importance as fine tuning of the geometry and material in combination with precision tool holding systems offer the prospect of finish hole capability within a few ~m. The field is now more active than it has ever been. Increased use of special designs involving new point geometries will bring improvements in life, penetration rates and chip control. New standards of manufacture, new materials and wider use of coatings offer the prospect of greater repeatability of performance and move away from the stigma that this is only a roughing tool. 14 ref. 53, Y. Ichihara, S. Kawata, I. Hikima, M. Hamatani, Y. Kudoh, A. Tanimoto, M. J. Lacombat, S. Wittekoek, "Illumination System of a Excimer Laser Stepper," SP1E - Optical microlithography and metrology for microcircuit fabrication, Vol 1138, Paris (France), 24-28 Apr 1989. pp. 137-145. Society of Photo-Optical Instrumentation Engineers. Bellingham, WA (USA). An illumination system suitable for an excimer laser stepper has been investigated. Unnecessary interference pattern (speckel) is reduced effectively by scanning the laser beam. The authors report spatial coherence of the lasers with different spectral line width, illumination system of the stepper, appearance of the interference pattern, its spacing and contrast and their relation to the illumination system and to the coherence of the laser. They report reduction of this pattern together with a simple method to measure its contrast. 54, E. Scholta, C. Schwanenberg, R. Zweiniger, "Increasing of Manufacturing Precision on Modern Machining Systems," Feingeraetetechnik, pp. 263-5. (1990). A high precision of the machining centre is a presupposition for precision machining. The application of automatically presettable drilling tools and the monitoring of the machine realized by a universal test standard and the integration of test procedures in the manufacturing process lead to further quality improvements in the automated operation. (German) 55, H. Shigematsu, S. Tomita, T. Odaki, "Influence of Cutting Fluid on Ultra-precision Turning of Aluminum with Natural Diamond Bite," Transactions of the Japan Society of Mechanical Engineers, Part C, 56(527), pp. 1947-1950. (Jul 1990). The examination on the phenomena which occurs between cutting edge of bite and worked surface in the wet turning was conducted. As the results, it was found that similar phenomena occur even when the kinds of cutting fluid were changed. Moreover, it was found that the contributions of extreme pressure additives of cutting fluid, or the diluting rate of water-base type cutting fluid to the effects on the phenomena which deteriorate worked surface. 2 Refs. (Japanese) 56, R. G. Bommakanti, T. S. Sudarshan, "Influence of Mechanical Grinding and Polishing Operations of Brittle Polycrystalline Alumina on the Pulsed Surface Flashover Performance," Journal of Applied Physics, pp. 6991-7. (1 June 1990). The degradation of the pulsed surface flashover performance of 99.9% pure polycrystalline alumina in an insulatorbridged vacuum gap, due to the mechanical grinding and finishing of the insulator is reported. The flashover characteristics of three different surface finishes-as-fired (0.8 ~tm), a ground surface (0.25 I.tm), and a polished surface (0.05 p.m) were studied using timecoordinated voltage, current, and luminosity diagnostics with a temporal resolution of approximately 1.5 ns, for 0.5/15 ~ts pulsed voltage excitations. The flashover strengths of the ground samples are lower than the as-fired sample by about 50% while the strengths of the polished surfaces are intermediate between the two. These results contradict earlier reports which attribute the lower holdoff of smooth finishes to the enhanced secondary emission yield as compared to the rougher surface finishes. The lower flashover strengths for the ground surface as compared to the as-fired surface are attributed by the authors to the surface defects consisting of intergranular and transgranular fracture features induced by the mechanical grinding operation. The improved performance of the polished surface over the ground surface is proposed to be due to the partial removal of the damage created during the grinding operations. The suggested increase in the defect density in the surface layers of ground and polished surfaces relative to the as-fired finish is substantiated by characteristic defect-dominated signatures in the luminosity-current profiles. These results are in agreement with an earlier report describing the role of trapped carriers in the flashover process. It is concluded that the insulating properties of the surface as influenced by the microstructural features are strongly dependent on the precise mode of material removal

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